<template>
  <div class="spec-preview">
    <img :src="skuImageList[defaultIndex]?.imgUrl" />
    <div class="event" @mousemove="mousemove"></div>
    <div class="big">
      <img :src="skuImageList[defaultIndex]?.imgUrl" ref="bigImg"/>
    </div>
    <div class="mask" ref="mask"></div>
  </div>
</template>

<script>
  export default {
    name: "Zoom",
    props:['skuImageList'],
    mounted() {
      this.$bus.$on("changeDefaultIndex", (index) => {
        this.defaultIndex = index;
      });
    },
    data(){
      return{
        defaultIndex:0
      }
    },
    methods:{
      mousemove(e){
      //  鼠标移动的时候获取鼠标距离外边距的距离
        const mouseDistance = {
          x : e.offsetX,
          y : e.offsetY
        }
        // console.log(mouseDistance.x,mouseDistance.y)
      //  计算蒙版的位置
        const maskW = this.$refs.mask.offsetWidth
        const maskH = this.$refs.mask.offsetHeight
        const maskLocation = {
          x : mouseDistance.x - maskW/2,
          y : mouseDistance.y - maskH/2
        }
        //  设置吸附效果
        if (maskLocation.x<20){
          maskLocation.x = 0
        }else if (maskLocation.x>e.target.clientWidth-maskW-20){
          maskLocation.x = e.target.clientWidth-maskW
        }
        if (maskLocation.y<20){
          maskLocation.y = 0
        }else if (maskLocation.y>e.target.clientHeight-maskW-20){
          maskLocation.y = e.target.clientHeight-maskW
        }
        //给蒙版位置赋值
        this.$refs.mask.style.left = maskLocation.x + 'px'
        this.$refs.mask.style.top = maskLocation.y + 'px'
      //  控制大图移动
        this.$refs.bigImg.style.left =- 2*maskLocation.x + 'px'
        this.$refs.bigImg.style.top =- 2*maskLocation.y + 'px'

      }
    }
  }
</script>

<style lang="less">
  .spec-preview {
    position: relative;
    width: 400px;
    height: 400px;
    border: 1px solid #ccc;

    img {
      width: 100%;
      height: 100%;
    }

    .event {
      width: 100%;
      height: 100%;
      position: absolute;
      top: 0;
      left: 0;
      z-index: 998;
    }

    .mask {
      width: 50%;
      height: 50%;
      background-color: rgba(0, 255, 0, 0.3);
      position: absolute;
      left: 0;
      top: 0;
      display: none;
    }

    .big {
      width: 100%;
      height: 100%;
      position: absolute;
      top: -1px;
      left: 100%;
      border: 1px solid #aaa;
      overflow: hidden;
      z-index: 998;
      display: none;
      background: white;

      img {
        width: 200%;
        max-width: 200%;
        height: 200%;
        position: absolute;
        left: 0;
        top: 0;
      }
    }

    .event:hover~.mask,
    .event:hover~.big {
      display: block;
    }
  }
</style>